VLA1553-403 Pregnancy Surveillance Study

February 9, 2026 updated by: Valneva Austria GmbH

Observational Study to Evaluate the Safety of Live-attenuated Chikungunya Virus Vaccine (VLA1553) in Pregnant Women Exposed to the Vaccine in Brazil

This post-marketing, observational study evaluates pregnancy and infant outcomes up to 12 weeks after delivery among women who received the chikungunya vaccine (VLA1553) during pregnancy or within 30 days before their last menstrual period. A matched comparator cohort of pregnant women vaccinated with routine, pregnancy-recommended vaccines (not exposed to VLA1553) is included. No study procedures beyond routine care are performed.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This is an observational, non-interventional study in pregnant women who were vaccinated with the live-attenuated chikungunya virus vaccine (VLA1553) anytime during their pregnancy or within 30 days preceding their last menstrual period (VLA1553 group). The study protocol includes a comparator group of routinely vaccinated pregnant women not exposed to VLA1553 (control group).

The VLA1553 and control groups will be matched by gestational trimester and maternal age range (women <35 years of age at the time of enrolment and women >35 years of age) at exposure time. The study will collect information including vaccine exposure, demographic information, pregnancy data (e.g., date of positive pregnancy test, expected delivery date, previous pregnancy information), and medical history. Furthermore, data on pregnancy and infant outcomes up to 12 weeks post expected delivery date (EDD) will be compiled. The EDD will be calculated by counting 40 weeks from the first day of the LMP. This approach involves collecting data from the participating women onto the database by site staff and, if possible, confirmed and expanded by their PS-HCP as needed. Additionally, with consent, medical records may be accessed by study staff to further verify and supplement the information. This study will not provide or make recommendations on any vaccine use. Participation in the study is voluntary. Participation or lack of participation in this study will not change or influence a participant's standard of care.

Study Type

Observational

Enrollment (Estimated)

200

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Valneva Late-Stage Clinical Development
  • Phone Number: +43 1 206 20 0
  • Email: office@valneva.com

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

The control group will consist of women who have received vaccine(s) approved for use during pregnancy by the MoH and who meet the matching criteria.

Description

Inclusion Criteria:

VLA1553 vaccinated population:

  • Women who have received the single dose of the VLA1553 vaccine during pregnancy or within the 30 days prior to the first day of the last menstrual period.
  • Pregnant at the time of enrolment in the study.
  • The participant understands and agrees to comply with the study procedures.

Control group:

  • Pregnant at the time of enrolment in the study.
  • Women who have received vaccine(s) approved for use during pregnancy by the MoH and who meet the matching criteria described in the protocol.
  • The participant understands and agrees to comply with the study procedures.
  • Women who have not received the VLA1553 vaccine during pregnancy or within the 30 days prior to the first day of the last menstrual period.

Exclusion Criteria:

  • Women who do not provide informed consent.
  • Women who are not part of the target population of the pilot vaccination strategy at the time of vaccination.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
VLA1553 group
Women vaccinated with the chikungunya virus vaccine (VLA1553) anytime during their pregnancy or within 30 days preceding their last menstrual period.
Biological: Live-attenuated CHIKV vaccine VLA1553
Non-interventional study: VLA1553 is used in the pilot vaccination strategy which will start along with this observational study.
Control group
Women who have received vaccine(s) approved for use during pregnancy by the MoH and who meet the matching criteria.
Biological: Vaccine(s) approved for use during pregnancy by the MoH
Vaccine(s) approved for use during pregnancy by the MoH

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Frequency (n,%) of individuals with any outcome (pregnancy and infant health), as described in the protocol.
Time Frame: Study start through study completion, an average of 12 months

Pregnancy and infant outcomes will be collected as follows:

  1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births.
  2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months
Frequency (n,%) of specific outcomes (pregnancy and infant health), as described in the protocol.
Time Frame: Study start through study completion, an average of 12 months

Pregnancy and infant outcomes will be collected as follows:

  1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births.
  2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Frequency (n,%) of individuals with any outcome (pregnancy and infant health), as described in the protocol in the VLA1553 group and the control group.
Time Frame: Study start through study completion, an average of 12 months
Pregnancy and infant outcomes will be collected as follows: 1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births. 2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months
Frequency (n,%) of specific outcomes (pregnancy and infant health), as described in the protocol in the VLA1553 group and the control group.
Time Frame: Study start through study completion, an average of 12 months
Pregnancy and infant outcomes will be collected as follows: 1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births. 2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months
Relative risk (RR) of any outcome (pregnancy and infant health) between pregnant women vaccinated with VLA1553 and pregnant women vaccinated with other vaccines recommended during pregnancy, as described in the protocol.
Time Frame: Study start through study completion, an average of 12 months
Pregnancy and infant outcomes will be collected as follows: 1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births. 2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months
Frequency (n,%) of individuals with SAEs (women and infants), following vaccination with VLA1553 or a control vaccine.
Time Frame: Study start through study completion, an average of 12 months
Pregnancy and infant outcomes will be collected as follows: 1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births. 2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Valneva Austria GmbH

Collaborators

Coalition for Epidemic Preparedness Innovations
Fundação Butantan

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

March 31, 2026

Primary Completion (Estimated)

December 31, 2027

Study Completion (Estimated)

December 31, 2027

Study Registration Dates

First Submitted

February 9, 2026

First Submitted That Met QC Criteria

February 9, 2026

First Posted (Actual)

February 17, 2026

Study Record Updates

Last Update Posted (Actual)

February 17, 2026

Last Update Submitted That Met QC Criteria

February 9, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • VLA1553-403

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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